The continuing trend of scaling down integrated circuits has motivated the semiconductor industry to consider new techniques for fabricating precise components at sub-micron levels. Along with the need for smaller components, there has been a growing demand for devices consuming less power. In the manufacture of memory devices, these trends have led the industry to refine approaches to achieve thinner capacitor cell dielectric and surface enhanced storage capacitor electrodes.
In dynamic random access memory (DRAM) devices it is essential that storage node capacitor cell plates be large enough to exhibit sufficient capacitance in order to retain an adequate charge in spite of parasitic capacitance and noise that may be present during circuit operation. As is the case for most semiconductor integrated circuitry, circuit density is continuing to increase at a fairly constant rate.
The issue of maintaining storage node capacitance is particularly important as the density of DRAM arrays continues to increase for future generations of memory devices. The ability to densely pack storage cells while maintaining required capacitance levels is a crucial requirement of semiconductor manufacturing technologies if future generations of expanded memory array devices are to be successfully manufactured.
One area of manufacturing technology that has emerged has been in the development of Hemi-Spherical Grain (HSG) silicon. HSG silicon enhances storage capacitance when used to form the storage node electrode without increasing the area required for the cell or the storage electrode height. The available methods known to those skilled in the art include use of Low Pressure Chemical Vapor Deposition (LPCVD) to deposit thin silicon films (conductively doped and non-doped silicon films) to form a rough surface. One method adds the silicon seeding and anneal steps in-situ and another method performs the silicon seeding and anneal in separate LPCVD systems. Methods to form HSG silicon, known to those skilled in the art, are utilized in conjunction with the several embodiments of the present invention that enhance the roughness of HSG silicon.
Embodiments of the present invention describe structures and the formation thereof which utilize hemi-spherical grain silicon material, the size and shape of which is enhanced by the use of epitaxial silicon, to be used in semiconductor structures for semiconductor assemblies, which will become apparent to those skilled in the art from the following disclosure.